1. Field of Invention
This invention relates to substituted polybenzimidazole products and a process for their production. More particularly, this invention relates to sulfoalkyl derivatives of polybenzimidazole and a process for their production.
2. Prior Art
Polybenzimidazole polymers are a known class of heterocyclic polymers which are characterized by a high degree of thermal and chemical stability. Processes for their production are disclosed in U.S. Pat. No. Re. 26,065 and U.S. Pat. Nos. 3,331,783, 3,509,108 and 3,555,539 among others. Polybenzimidazole polymers have been formed into membranes, ultrafilters, ion exchange resins and for numerous other separatory devices.
Although polybenzimidazole polymers are generally more resistant to chemical reaction than other types of polymers, such as cellulose acetate polymers, under certain circumstances, reaction at the imidazole nitrogen-hydrogen bond will occur. One means of avoiding this reaction is to chemically modify the polybenzimidazole polymer, for example, by crosslinking the polymer as is disclosed in U.S. Pat. Nos. 4,020,142 and 4,154,919.
Another method of reducing the chemical reactivity of the polybenzimidazole polymer is by replacing the imidazole hydrogen with a less reactive substituent. For example, U.S. Pat. No. 4,377,546 discloses a substituted polybenzimidazole polymer wherein the hydrogen on the imidazole nitrogen has been replaced by a phenyl group. U.S. Pat. No. 3,578,644 discloses an hydroxyethyl substituent on a polybenzimidazole polymer produced by the reaction of a polybenzimidazole polymer with an omega-halo-alkanol or a 1,2-alkylene oxide. U.S. Pat. No. 4,599,388 also discloses a process for the production of hydroxyethylated polybenzimidazole polymers. However, none of these patents disclose sulfoalkyl derivatives of polybenzimidazole polymers.
U.S. Pat. No. 3,943,125 discloses a vast array of substituted polybenzimidazole polymers which are produced by the reaction of substituted tetramino pyridines or their acid salts with a suitable acid halide or dianhydride. The resulting precyclized intermediates are cyclodehydrated and crosslinked to produce various substituted polybenzimidazole polymers. However, the percentage of substitution of the polybenzimidazole polymers produced by this reaction ranges only between 20 and 40 percent of the available imidazole hydrogen sites. Further, the process of the '125 patent is significantly different from the process of the instant invention.
U.S. Pat. No. 3,518,234 discloses a process for the preparation of N-aryl substituted polybenzimidazole polymers. However, the substituted polybenzimidazole polymers are not produced by direct reaction with a polybenzimidazole polymer and substantial heating of the reaction vehicle is necessary. Further, no sulfoalkyl derivatives of polybenzimidazole are disclosed.
Technical reports published by Celanese Research Company (AD-755356, dated January, 1974) and Fabric Research Laboratories (AFML-TR-73-29, dated December, 1971) disclose a process for sulfonating polybenzimidazole fiber in order to reduce its thermal shrinkage. However, these reports do not disclose a process for sulfoalkylating polybenzimidazole by the process of the instant invention.
It is therefore an object of this invention to provide a process for the preparation of novel sulfoalkyl polybenzimidazole polymers.
It is an additional object of this invention to provide a process for the preparation of novel sulfoalkyl polybenzimidazole polymers using a sultone.
It is a further object of this invention is to prepare novel sulfoalkylated polybenzimidazole polymers that exhibit a high degree of chemical and thermal stability.
It is a still further object of this invention to prepare sulfoalkylated polybenzimidazole polymers for use as separatory devices.
These and other objects as well as the scope, nature and utilization of this invention are apparent to those skilled in the art from the following detailed description and appended claims.